1. Field of the Invention
The present invention relates to couplings for structurally connecting and orificially connecting gas and/or liquid gas supply containers to control valves and/or other outlet ports, and more particularly to couplings used with portable and/or disposable liquid gas cannisters.
2. Brief Description of the Prior Art
The predominant world wide method for mechanically connecting a fuel supply control valve to a portable supply container is to use mating screw threads. Screw threads are also the predominant means of connection for larger fuel containers such as a welding tanks or large propane tanks, and these larger containers also have control valves governing outlet orifices to which a regulator can be attached when the valve is shut off. However, smaller and especially disposable fuel containers have very simple orifice valves which allow the escape of fuel as soon as insertion of a male needle valve orifice typical of the conventional control valves available occurs.
These conventional control valves made for the portable and disposable type fuel cannisters normally have a throat surrounding their inlet needle orifices, with internal screw threads that receive the external screw threads of a raised neck surrounding the outlet orifice of the cannister. When the control valve is screwed onto the cannister the seals about the needle valve orifice and the cannister orifice come into contact as the orifices connect with continued screwing of the threads. This is exemplified by commonly used portable propane torches, portable gas stoves and the like.
In addition to some of the more common disadvantages of using screw threads for repeated engagement or disengagement of parts such as the speed and ease of the connection, or the wearing, stripping, corroding, or other compromising of the screw threads mechanical integrity, there are problems specific to the type of connection presently discussed.
When a conventional fuel control valve is screwed onto a conventional fuel cannister there is a period when the connection of orifices is occurring but not sealed. By varying the pitch of the threads this period can be minimized, but not eliminated. Therefore leakage of fuel during both the engagement and disengagement of the control valve, as well as possible sustained leakage caused by incomplete screwing, or inadvertent unscrewing of the control valve constitutes a serious and possibly dangerous disadvantage to using screw threads for this type of connection.
An alternative coupling solution is used by Camping Gaz International.TM., and disclosed in French patent no 8 701 097, and European patent no. 0 278 873, the named inventor is Daniel Finand. Finands cannister does not use screw threads. As exemplified by the Camping Gaz International.TM. CV 470 cartridge, DOT - E 9758, CTC SP 2739, the cannister orifice is in a raised nipple which is centered in a cylindrical throat recessed into the cannister. This throat is characterized by an involuted lip around its rim, and a depression or groove formed beneath the rim around the interior perimeter of the throat.
Finands corresponding control valve has a probiscus-like extension of the control valve inlet, housing the needle valve orifice near its end. This inlet stalk has external screw threads which mate with internal screw threads in a large plastic coupling member. This plastic member is a cylinder which by turning on the screw threads moves up or down the inlet stalk. It is characterized by a large radially extended wheel, which has vertical ridges around its perimeter for manual gripping, and turns the entire plastic member about the inlet stalk. The bottom of the plastic cylinder within the wheel is cut into four sections below the screw threads that form four elastic prongs which are juxtaposed to the lower portion of the inlet stalk. The lowermost end of the inlet stalk has a flared back rim just above the lowermost ends of the four plastic prongs, which also have corresponding angled lips facing the inlet rim. Each prong has on its outer side, opposite the angled lips, a projected angular ridge.
The coupling works by setting the control valve onto the cannister so that the plastic prongs are beneath the inlet rim and easily inserted beneath the inside lip of the throat. Whereupon as the plastic wheel is turned the plastic member moves up the inlet stalk pulling the angled ends of the prongs against the flared rim of the inlet stalk. This forces the elastic prongs outwardly and the projected angular edges of the prongs key into the annular groove beneath the involuted lip of the cannister throat. With the prongs caught in the throat of the cannister, continued turning of the wheel forces the inlet stalk down over the cannister outlet nipple. The needle valve inside the inlet stalk is thusly inserted into the cannister outlet orifice.
The problem with Finands coupling solution is that screw threads still drive the engaging and disengaging mechanisms. Accordingly, leakage is no less a problem if not worse than the conventional solutions, in that the plastic screw threaded portion has even more of a propensity to partially unscrew during normal use and movement of the parts. Therefore the need is evident for a coupling mechanism where engagement and/or disengagement is not driven by the turning of screw threads.